Metal-pickle and method of pickling.



LOUIS DREFAHL, OF CLEVELAND, OHIO, ASSIGNOB, TO THE GRASSELLI CfiEMICALCOMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

METAL-PICKLE AND METHOD OF PICKLING.

1,191,291, No Drawing.

. herein explained and the best mode in which I have contemplatedapplying that principle, so as to distinguish it from other inventions.

The present improvements, relating as indicated to a metal pickle andmethods of pickling, have more particular regard to the avoidance of theobjectionable efi'ervescing or-spraying of fine particles of liquid fromthe usual pickling compound, these drops of liquid being acid and beingvery injurious, not only to the surroundings of the pickling tanks, butalso to any workmen who may be in the vicinity.

To the accomplishment of the foregoing and related ends, said invention,then, consists of the means hereinafter fully described and particularlypointed out in the claims.

The following description sets forth in detail one approved method ofcarrying-out the invention, such disclosed mode, however, constitutingbut one of the various Ways in which the principle of the invention maybe used.

The most commonly used pickling compounds for removing the scale frommetal articles, (this scale usually consisting of an oxid of the metal)contain acids such as sulfuric or muriatic acids, or salts which containappreciable quantities of free acids which act upon the scale on themetal to dissolve it, at the same time forming gas, which of coursebubbles out of the liquid with suflicient violence to produce a mist orspray containing a certain amount of the acid solution. This spray is ofcourse, very injurious to the surroundings of the tanks and to theoperators. I have discovered a method of preventing this objectionablespray or mist and I accomplish this desirable end in a very simple andinexpensive manner by the use of a substance which in no 'way affectsthe action of the pickling compound.

My invention involves the use of cellulose pulp waste in a picklingcompound, whether the latter consists of an acid solution or some acidcontaining salt such as niter cake or the Specification of LettersPatent.

Application filed February 19, 1916. Serial No. 79,817.

Patented J uly18 1916.

like. This pulp waste may be used in'vary- 1ng amounts since it takes nopart in the reactlon on the metal, but serves only to produce a heavyfoam or lather on the bath when any gas is evolved. Until gas is givenoff, the pulp waste remains quiescent in the pickling bath, but as soonas any metal.

articles are put in, and the acid of the solution attacks thesearticles, the gas given off produces a th1ck foam on the top of the"bath. This foam has but one function, and that is, to serve as a filteror blanket for removing the particles of liquid from the gas. In thisway, the evolution. of gas is prevented from causing any spraying orefl'er-Q I vescing of liquid, and consequently no lnjury is done to thesurroundings or the operators.-

As soon as the evolution of gas ceases, the

foam disappears, but is at once formed again when more gas 1s given off.

A convenient method of introducing the pulp waste in a pickling solutionof niter cake is to add a small amount of the liquid cellulose pulpwaste to the niter cake before the latter is sent to the pickling bath,

although it may be added directly to the bath if desired. The amount isdetermined largely by the violence of the reaction, since the greaterthe evolution of gas, the heavier the foam must be to prevent thespraying of particles of liquid through it. Since the cellulose pulpwaste takes no part in the pickling action, it follows that it may beadded in various amounts without detriment to the effectiveness of thepickling compound. I

prefer ordinarily to use cellulose pulp waste.

to the extent of about 5 or 6% of the Weight of the pickling compound.

In case the pickling bath is a straight acid solution such as sulfuricacid for example,

then a vconvenient method of adding the cellulose pulp Waste is in thedried form. This dried pulp waste is added directly to the picklingsolution in approximately the same proportions as when used in theliquidstate and preferably will be first mixed with twice its weight ofcopperas which, While serving no useful purpose in the picklingsolution, is the same substance as the resulting-solution after thereaction upon the metal articles, namely ferrous sulfate. It will beappreciated that other substances than copperas may be employed with thedried cellulose.

pulp waste, provided they do not interfere 1. A metal pickling bathwhich consists of an acid containing substance and cellulose pulp waste.

2. A metal pickling bath which consists of or steps stated by any ofiaaaeei an acid .containing substance and a small amount of cellulosepul waste.

, 3. A metal pickling of an acid containing substance and approximatelysix per cent. (6%) of cellulose pulp waste.

4. In a methodof preventing the efiervescing of a metalpickling'solution the step which consists in adding to such solution asmall amount of cellulose pulp waste, thereby producing a thick foam onsuch solution.

Signed by me, this 16' day of February,

LOUIS O. DREFAHL.

Attested by-' W. T. CAsHMAN, E. R. Bauer.

ath which consists

